The present invention relates to an adjustment device. More particularly this invention concerns a knob usable on a device for adjusting the position of a motor-vehicle seat.
It is known to provide a vehicle seat with an adjustment mechanism such as described in the commonly assigned and copending patent application Ser. No. 544,780, now U.S. Pat. No. 3,976,327 and 572,300, now U.S. Pat. No. 3,966,253, filed Jan. 28, 1975, and Mar. 28, 1975, respectively. Such devices normally are operated by a knob provided at the hinge between the back part and the seat part of the motor-vehicle seat. This knob can either be rotated to loosen a setting arrangement that allows the back to be displaced and then tightened again in another position, or it allows the rotation of a cam having surfaces that establish different rest positions for the back part of the seat.
The knob that operates this adjustment device is normally of relatively large diameter and made of synthetic-resin material. Its principal functions are to cover and protect the mechanism of the adjustment device and to provide the user with a good grip on the adjustment member of this device.
Such a knob is frequently formed as a synthetic-resin ring which is fitted around the metal adjustment member and is then clamped in place by a disc or the like that is screwed to the face of the adjustment member. Such a structure has the disadvantage of relatively high fabrication costs due to the two-part construction that must in addition be held in place by supplemental screws. Furthermore such arrangements occasionally break, as they are unable to transmit sufficient torque between the synthetic-resin knob part and the metal adjustment member. Also it is noted that the particular position of such a knob, at the lower part of the back of the front seat exposes it to occasionally considerable physical stressing, particularly when people climbing into or out of the back seat of a two-door vehicle step on or kick this knob.
A prior-art knob can be seen in German Pat. No. 1,755,310.